Mid-late holocene sea-level variability in eastern Australia

A re-analysis of sea-level data from eastern Australia based on 115 calibrated C-14 ages is used to constrain the origin, timing and magnitude of sea-level change over the last 7000 years. We demonstrate that the Holocene sea-level highstand of +1.0-1.5 m was reached similar to 7000 cal yr Bp and fell to its present position after 2000 yr Bp. These findings are in contrast to most previous studies that relied on smaller datasets and did not include the now common conversion of conventional C-14 ages to calendar years. During this similar to 5000 year period of high sea level, growth hiatuses in oyster beds and tubeworms and lower elevations of coral microatolls are interpreted to represent short-lived oscillations in sea-level of up to 1 m during two intervals, beginning c. 4800 and 3000 cal yr Bp. The rates of sea-level rise and fall (1-2 mm yr(-1)) during these centennial-scale oscillations are comparable with current rates of sea-level rise. The origin of the oscillations is enigmatic but most likely the result of oceanographic and climatic changes, including wind strengths, ice ablation, and melt-water contributions of both Greenland and Antarctic ice sheets.